1. Field of the Invention
The present invention relates to a colored plastics molding device, particularly, to a colored plastics molding device which colors the raw plastics material for molding having a thermoplasticity by mixing it with a liquid colorant for molding.
2. Prior Art
As an example of conventional device of this type, a device comprising a hopper which stores and discharges the raw plastics material; a conveying means which comprises a screw disposed on the discharge side of the hopper; and a head which compresses the raw plastics material conveyed by this conveying means while supplying it to the mold or the like is well known.
However, with said conventional device, the raw plastics material is mixed with a colorant liquid color) inside the hopper when the raw plastics material is to be colored with a colorant for obtaining a colored molded item.
To accurately determine the set quantity of colorant, it is necessary to make calibration for each particular colorant used, because the delivery varies depending upon the specific gravity and viscosity of the colorant used.
Conventionally, a small container, such as a plastic cup, a paper cup, and a beaker, is prepared, and the tare is accurately measured.
Then, the air bubbles and the like included in the tube (pump) is completely removed.
For example, if the values of set quantity are 50 and 200, the calibration operation is:
First, the signal key is depressed to allow a discharge signal to be given as in molding. Discharge is made 20 times or more. The more the number of discharge times, the more accurate the calibration.
A graph is drawn with the set quantity being chosen as the axis of abscissa, and the delivery as the axis of ordinates. For example, if the set quantity is 200, and the colorant delivery of 20 times in total is 16 g, the delivery of one time is 0.8 g, and if the set quantity is 50, and the colorant delivery of 20 times in total is 4 g, the delivery of one time is 0.2 g. When a plot is made of the above values of set quantity and delivery of one time, a graph of reference line as shown in FIG. 5 is obtained.
However, in the above example of conventional device, discharge is made 20 times or more, thus, if the number of discharge times should be wrongly counted, the result of computation of the delivery of one time tends to be greatly affected because the value of it is small.
The present invention has been developed in consideration of the above conventional situation, and the purpose of it is to provide a colored plastics molding device with which calibration is automatically performed, and thus the colorant can be charged, being free from wrong calculation and error, therefore, high-quality colored plastics molded items can be obtained.
The invention provides a colored plastics molding device comprising: a raw plastics material supply means which stores a raw plastics material for molding having a thermoplasticity and discharges the raw plastics material stored; a cylindrical transfer member which transfers the raw plastics material from this raw plastics material supply means; a colorant supply means which supplies a liquid colorant to the inside of said transfer member, the discharge end of a freely replaceable nozzle being disposed there; a conveying means which mixes the raw plastics material fed through said transfer means with the colorant, while conveying the mixture for molding; a detection means which detects the conveying state of said conveying means; and a control means which performs operation control of said colorant supply means on the basis of the result of detection by this detection means; wherein said colorant supply means has an automatic calibration function which allows automatic setting of the quantity of liquid colorant to be supplied.
The invention provides a colored plastics molding device wherein said colorant supply means has functions of setting of colorant set quantity, setting of speed, and setting of number of calibration discharge times; the value of total delivery of colorant is determined; and from the value of total delivery of colorant and the number of calibration discharge times, the value of delivery of colorant for one calibration discharge time is determined.
According to the invention, calibration is automatically performed, and thus the colorant can be charged, being free from wrong calculation and error, therefore, high-quality colored plastics molded items can be obtained.